Depolarization process for petroleum fractions



i atented May 22, 195i DEPOLARIZATION PROCESS FOR PETROLEUM FRACTIONS Clyve C. Allen, Cyril, kla., assignor to Anderson= Prichard Oil Corporation,

Oklahoma City,

Okla., a corporation of Delaware No Drawing, Application August 18, 1949, Serial No. 111,087

13 Claims. (Cl. 19640) The present invention relates to ways and means for removing polar or polarizable molecule content from natural petroleum fractions.

Natural petroleum fractions contain polarizable hydrocarbons, that is, olefins and aromatics, in amounts varying in accordance with the origin of the fraction. Such fractions may also contain various non-hydrocarbon components, such as sulphur compounds, nitrogen bodies, oxygencontaining substances, the amounts of which also vary according to the origin of the fraction. Such polarizable and polar molecule content usually runs from two to six per cent in best quality regularly refined straight-run petroleum fractions.

The presence of such polarizable components in petroleum fractions is undesirable for two or three major reasons:

First, a wholly paraifinic and/or cycloparaffinic fraction may be obtained, only if such undesirable polarizable molecular content is removed, and it is a well known fact that truly paraffinic hydrocarbon products are most desirable in many instances.

Second, unpleasant odors are removed, and

the resultant fraction is given a neutral or pleasant rain-water-like odor, instead of the usual kerosene-like or refinery odor which is present in most polarizable and polar fractions.

The word depolarization, as used herein, means the removal from petroleum fractions of all, or substantially all, polarized and/or polarizable hydrocarbon and non-hydrocarbon components.

The prime object of the present invention is to provide a process which will efliciently depolarize petroleum fractions.

In carrying forth the process of the present invention, certain rigidly controlled refining steps or stages are fitted together in series. Briefly stated, these stages include the following described steps:

Stage I Step 1.R.epeated or continuous agitation of a selected petroleum fraction in the presence of fresh portions of sulfuric acid.

Step 2.Removing reaction products in the acid phase after each period of agitation.

Stage II Step 1.-Agitation of the acid-treated fraction in the presence of aqueous caustic (repeatedly if desired).

Step 2.Removing reaction products in the aqueous phase (after each period of agitation, if plural periods are used).

2 Stage III Step 1.Agitation of the acid-treated and caustic-treated fraction in the presence of absorbent clay.

Step 2.Removing reaction products with the clay.

The present process has some similarity to general or conventional oil refining and/or deodorization processes, but is an improvement over such conventional processes due to the distinctive control features, and the stage and step intercombination.

In acid treating petroleum fractions by conventional or prior art processes, it has been found that the treated fraction is thereby given a much raised end-point, due to polymers, oil-soluble sulfuric esters, or condensation products which remain dissolved in the fraction. It has been discovered that under the multiple portion-byportion acid contacting, or counter current continuous contacting of the present process, all of the reaction products can be extracted along with the acid, and consequently, the end-point increase of conventional processes is thereby eliminated.

Some features of novelty and improvement which constitute portions of the present process are:

In Stage I above set forth, the acid is properly apportioned in the successive separate contacting and agitating periods, and appropriate time allowances are made for each period, so that: (a) polar substances are attacked and dissolved or entrained in the acid, and are removed with the resultant sludge from the fraction being treated; and (b), polarizable hydrocarbons and oil-soluble reaction products are also entrained in the acid, and-are removed with the acid from the fraction.

Tests made on petroleum fractions treated by the present process, show that the depolarized naphtha has a distillation end-point equal, substantially, to that of the charge stock. This is evidence that the present process does not increase the distillation end-point of the fraction over that of the charge stock, as is present in conventional acid treating processes.

Evidence that polar substances, polarizable hydrocarbons, and oil soluble reaction products have been removed from the oil fraction is indicated, in part, by the absence of color therein after test agitating the product in the presence of concentrated (syrupy) phosphoric acid at ordinary temperatures. Verification of such removal is also evidenced by the absence of the usual kerosene or refinery odor in the resultant attaca 3 product, which has a pleasant neutral rainwater-like odor which is characteristic of truly apolar oil. Such odor, if course, varies to some extent with the various proportions of parafiins and cycloparafiins present in the product.

Confirmation that such removal has been accomplished may also be proven by exposure of the treated product to intense ultraviolet light rays for a period of time more than suificient to break-down any actinic-sensitive polymers, esters, or condensation products which might be present. When so exposed, fractions which have been treated under the present process remain constant in color and clearness when tested under the ultraviolet rays. If proper extraction had not been accomplished, the rays would visibly evidence turbid or colored decomposition matter.

The present process has been found practical in treating any petroleum distillate fraction having a specific gravity less than approximately 0.87 at sixty degrees Fahrenheit, and having a viscosity below 210 Saybolt, at one hundred degrees Fahrenheit.

The processing may be conducted in one or a plurality of contacting vessels of the agitator type, and agitation for any processing step may be had by any desired means.

The acid used in connection with Stage I of the process can be of any desired strength of from about ninety-seven per cent to twenty-five per cent fuming, the high strength oleum being preferred.

The removal of the acid phase in step 2 of Stage I may be accomplished by either centrifuging or by gravitation.

The aqueous caustic for the treating of Stage II may well be sodium hydroxide or potassium hydroxide of any strength from about two per cent to about twenty-five cent, and withdrawal of the reaction products along with the alkaline aqueous phase may be accomplished by centrifuging, or by settling and draining.

The absorbent clay used in Stage III may well be bauxite, activated alumina, active magnesia, activated diatomaceous earth, or fullers earth, either in coarse granules or in finely powdered form, and separation of the reaction products along with the clay may be accomplished under step 2 of Stage III by decautation or by filtration.

In repeatedly carrying out step 1 of Stage I of the process a sufiicient number of times to obtain the desired results, the sulphuric acid requirement has been found to be from fifty to two hundred pounds per barrel of fraction treated, the varied requirement apparently depending upon the type of polar and polarizable compounds initially present in the fraction. The acid contacting and agitating step is repeated from five to fifteen times, with approximately equal divisions of the acid requirement being used each time. Each contacting period requires vigorous, intimate agitation for from'five to ninety minutes. It is necessary that the acid reaction product sludge be extracted as rapidly as possible after each acid contacting step, and before another step or a repeated step is begun.

When processing moist oil, one or two initial five minute contacting periods are used with barely enough acid present to dry the oil. This procedure has been found to reduce total acid requirement.

When air or gas agitation is used for processing with strong oleum, a fifteen minute period of mild mixing is employed before increasing to vigorous 4 agitation, in order to allow the sulphur trioxide to react, rather than being carried away.

When sludge separation is carried out by settling, sludge is preferably drawn off about as fast as it settles out. This saves time, and also acidit has been found that long standing of spent acid with oil in process tends to contaminate the oil with colored substances formed apparently by slow reaction in the acid phase.

If settling vessel design (or the wall surface) is inappropriate for fast settling by gravity, it is expedient to transfer the oil to a clean vessel after each acid contact, or rinse the oil and settling chamber walls with diluted (approx. 50%) sulfuric acid, which is an excellent sludge solvent.

Referring to Stage II of our depolarization process, it has been found that if Stage I has been accomplished, Stage II is exceedingly simple, requiring only a slight excess of alkali over the stoichiometrical requirement of the sulphur dioxide and traces of other acidic residues remaining in the acid treated oil. About 30 minutes moderate agitation, and up to 30 minutes settling, (depending on the oil gravity) are sufficient to produce a clear permanently neutral-reacting oil. It is pointed out that the present process is a very substantial improvement over prior art in this respect. Acid-treating investigators have heretofore made numerous reports of encountering persistent emulsion, and later development of turbidity and acidity in oils neutralized by aqueous caustic-evidently from residual acidic or ester substances in the acidtreated oil. Some investigators solved this problem by the expensive use of alcoholic caustic Washes.

Stage III is also readily performed, when Stage I has been controlled correctly, by approximately 45 minutes moderate agitation with 3 to '7 lbs. per barrel of good quality absorbent clay to remove dissolved water and suspensions of microscopic sized aqueous caustic or salt particles. High clay consumption by emulsified water is avoided in my process.

Hereinbelow are given some illustrative examples of carrying out the invention.

Example 1.A 42 gallon charge of mediumboiling petroleum fraction, 418 degrees F. initial, 473 degrees F. dry point, was agitated vigorously for five mnutes with 7.5 lbs. of 20% fuming oleum, by air-blowing plus high speed propeller stirring in a polished nickel alloy mixing vessel. The mixture was then allowed to settle with no agitation for 30 minutes, removing sludge through a bottom draw-on as fast as it collected, and completely, including wall run-off.

Fresh 20% fuming oleum, 14 lbs, was then added to the oil and vigorous agitation repeated for five minutes, settling repeated for 30 minutes, drawing ofi sludge as before.

Fresh 20% fuming oleum, 15.7 lbs., was then added to the oil and the mixture agitated gently for 15 minutes, then vigorously for 45 minutes, settled 30 minutes and sludge completely separated off. This step was then repeated four times more. Small samples of the oil were removed after each step.

Aqueous sodium hydroxide, 2.6 gallons of 6 degree Be. strength, was added to the oil and agitated vigorously for 45 minutes, settled 30 minutes, and the aqueous layer dumped.

Bauxite fines, 7.5 lbs., was added to the oil, agitated vigorously for 45 minutes, then separated off through a filter press.

whatever were detectable.

The small samples of the oil removed during the Stage I processing were each treated with aqueous caustic and clay in proportion as in the main batch and inspected, with the results tabulated herebelow:

A repetition of Example 1 was made using identical materials and equipment, but condensing the last four acid contactings into two 31.4 lbs. oleum per barrel contactings. This processing, of total 100 lbs. oleum per barrel, yielded product indistinguishable from the previous instream sample of 84.3 lbs. oleum per barrel.

The Example 1 processing also was extended to include two additional 15.7 lbs. oleum per bbl. contactings. The product from this 131.4 lbs. oleum per barrel experiment was identical in properties to the previous main product.

Example 2.-A naphtha fraction boiling 358 degrees initial, 412 degrees dry point, was charged to 240 bbl. gauge into an air type agitator (oil temperature 140 degrees F.). The oil was processed as logged below, grabbing samples at steps Nos. V, VI, and VII, for completing treating by hand:

Treating schedule I. Oleum 55 gallon (20% fuming) put in, blown 5 minutes, drawn off.

II. Oleum, 110 gallons, put in, blown 5 minutes, settled 30 minutes, dumped.

III. Oleum, 260 gallons, added, blown 60 minutes, settled and drawn off over 30 min. period.

IV. Same as III.

V. Same as III.

VI. Same as III.

VII. Same as III.

VIII. Aqueous caustic, 6 degrees B., 350 gallons, was put in and blown 30 minutes, settled 30 min. and drawn ofi.

IX. Bauxite fines, 1000 lbs, was added and blown 45 minutes, then filtered ofi through a press in transferring the oil to storage.

Processing was not carried out continuously from step V on. Operators waited on results of hand testing of in-process samples.

Samples from each of steps V, VI, and VII were laboratory caustic-scrubbed and clay clarified. Also, a duplicate of sample VII was contacted with an additional 1.1 gallons of oleum per barrel, then caustic and clay treated.

The laboratory reported acid-treats VI and VII necessary and s'umcient for completing Stage I complete depolarization except for suspended and dissolved inorganic acidic residues and moisture.

The main product distilled 359 degrees initial, 412 degrees dry point, Saybolt color 30 plus, gave no sludge withconcentrated phosphoric acid, was stable to ultra-violet light exposure and possessed a pleasant rain-water-like odor.

A substantial portion of the product was put through a comprehensive series of garment drycleaning tests, employing standard practises. The tests showed:

The depolarized solvent made a better working atmosphere for handlers by eliminating mineral spirits odor.

'Ilie depolarized solvent improved cleaning results by elimination of extracted naphtha residual odor.

Increased plant capacity by reducing tumbling time without increasing fire hazard.

Increased plant capacity by offering no opposing polar attraction to the action of the clarifier, thereby reducing acid and saponifiable build-up in the solvent.

Increased plant capacity by the complete oxidation stability of the solvent slowing down solvent deterioration.

Example 3.-A 238 barrel batch of naptha distilling 320 degrees F. initial boiling point, 394 degrees F. dry point, was processed exactly as in Example 2, except that 417 gallons of 5 degrees Be. aqueous caustic was used in the next to last step, and 300 lbs. of 40 to 60 mesh activated alumina was taken for the last step, instead of bauxite.

The process was accompanied by hand-treating as in Example 2 to identify completion of Stage I. Several physical properties were determined, as. a matter of interest, on the hand-treated samples:

Properties of z'n-stream swmples hand-finished The main product distilled 326 degrees F. initial boiling point, 396 degrees F. dry point, and was otherwise identical in apolar characteristics like the Example 1 and Example 2 products.

Portions of Examples 1, 2, and 3 main products were given a thorough odor test schedule as paint and enamel thinners, using conventional pigments, oils and resins and comparing with identical compositions formulated with standard regular quality thinners and with all available commercial deodorized thinners.

The tests were conducted by smelling the paints and enamels from open cans, smelling the mists from spray guns, smelling coated surfaces at intervals during drying, and smelling through apertures in interior spray-coated boxes, built especially to slow down solvent evaporation. In all cases the odors of the formulations from the depolarized oils were by far more pleasant than from analogous compositions containing regular quality thinners and were judged as more agrees if able than similar compositions with deodorized thinners.

The efiect of employing depolarized thinners was found to be quite impressiveonly rather attractive resinous or balsam-like odors were apparent during and after application.

A portion of Example 3 main product was subjected to an exhaustive series of bio-assay tests against laboratory reared colonies of house flies. The depolarized naphtha was employed as carrier for residual insecticides (DDT, highgamrna isomer BHC, Chlordane, and Toxaphene) and tested in comparison with *deodorized insecticide'spray base oils on the mamet. Example 3 main product Was found to be superior to ,all of the other vehicles.

Example 1.-Naphtha as in Example 3 was processed as in Example 3, .except that the .acid sludge resulting from steps V, VI and VII of Example 3 Was used as a replacement for the first two acid contacts. Results wereequivalent in every measurable quality of the iii-process control samples main product; hence 155 gallons of fresh oleum were saved per 240 bar.- rels of naphtha processed, by re-use of thesludge.

The herein-above described test examples bear out the fact that the present invented process is capable of eificiently depolarizing petroleum fractions, and is a vast improvement over conventional practices, as evidenced by means of mutually confirmatory tests on. in-streamsarnples taken during processing, and which show that the resultant product is characterized by relatively low dry-point, no sludging coloration with concentrated phosphoric acid, comparatively high stability to actinic action, and the absence of mineral spirits or kerosene odor.

I claim:

1. A process for manufacturing aromatic free depolarized naphtha from petroleum distillate, characterized by: contacting the petroleum fraction with strong sulphuric acid in at least three stages; testing in-stream samples following the third stage and following each succeeding stage; continuing said acid contacting andsaid testing until the fraction is found to be substantially free of polar organic substances, as evidenced by relatively low dry-point, no sludging coloration with concentrated phosphoric acid, a comparatively high stability to actinic action, the absence of mineral spirits odor and the absence of kerosene smell; and then finally removing inorganic contaminants by aqueous caustic scrubbing and also by absorbent clay contacting.

2. A process for manufacturing aromatic free depolarized naphtha from petroleum distillate, characterized by: contacting the petroleumfraction with strong sulphu ic acid in at least three stages; esting lll-s'illonlil samples following the third stage and following each succeeding stage for dry point, sludging coloration with concentrated phosphoric acid, stability to actinic .action, and presence of mineral spirits odor and kerosene smell; continuing said sulphuric acid contacting until said tests show the fraction to be substantially free of polar organicsubstances; and then finally removing inorganic contaminants by aqueous caustic scrubbing and also by absorbent clay contacting.

3. A process for manufacturing aromatic-free depolarized naphtha from medium and low boiling petroleum distillates, characterized by: contacting. the petroleum. fraction with strong s ulphoric acidzin at leastv three stages;;.testing instrearn' samples following the third stage and following each succeeding stage; continuing said acid contacting and said testing until the fraction is found to be substantially free of polar organic substances, as evidenced by relatively low dry-point, no sludging coloration with concentrated phosphoric acid, a comparatively high stability to actinic action, and the absence of mineral spirits odor and kerosene smell; and then iinally removing inorganic contaminants by aqueous caustic scrubbing and also by absorbent clay contacting.

fl. A process for manufacturing aromatic free depolarized naphtha from medium and low boiling petroleum distillates, characterized by: contacting the petroleum fraction with strong sulphuric acid in at least three stages; testing in- .stream samples following the third stage and following each succeeding stage for dry point, sludging coloration with concentrated phosphoric acid, stability .to actinic action, and presence of mineral spirits odor and kerosene smell; continuing said sulphuric acid contacting and said testing until said tests show the fraction to be substantially free of polar organic substances; and then finally removing inorganic contaminants by aqueous caustic scrubbing and also by absorbent clay contacting.

5. A process for manufacturing aromatic free depolarized naphtha from petroleum distillate, characterized by: contacting the petroleum fraction with strong sulphuric acid in at least three stages; testing in-stream samples following the third stage and following each succeeding stage;

continuing said acidcontacting andsaid testing until the fraction is found to be substantially free of polar organic substances, as evidenced by relatively low dry-point, no sludging coloration with concentrated phosphoric acid, a com paratively high stability to actinic action, and the absence of mineral spirits odor and kerosene smell; and then finally removing inorganic contaminants by aqueous caustic scrubbing and also by absorbent clay contacting] fivA processfor manufacturing aromatic free depolarized naphtha from petroleumdis'tillate, characterized by: continuously contacting "the petroleum fraction with strong sulphuric acid in at least three stages; testing in-stream samples following the third stage and following each succeeding stage; continuing said acid contacting and said testing until the fraction is found to be substantially free of polar organic substances, as evidenced by relatively low dry-point, no sludging coloration with concentrated phosphoric acid, a comparatively high stability to actinic action, and the absence of mineral spirits odor and kerosene smell; and then finally removing inorganic contaminants by aqueous caustic scrubbing and also byabsorbent clay contacting.

7. .A process for manufacturing aromatic free depolarized naphtha from petroleum distillate,

characterized by: continuously contacting the petroleum fraction with strong sulphuric acid in at least three stages; testing in-stream samples following the third stage and following each succeeding stage for dry point, sludging coloration with concentrated phosphoric acid, stability to actinic action, and presence of mineral spirits odor .and kerosene smell; continuing said sul phuric acid contacting and said testing until said tests show the fraction to besubstantially free of polar organic substances; and then finally removing.inorganiccontaminants by aquedu'scaus- 9 tic scrubbing and also by absorbent clay contacting.

8. A process for manufacturing aromatic free depolarized naphtha from medium and lolv boiling petroleum distillates, characterized by: continuously contacting the petroleum fraction with strong sulphuric acid in at least three stages; testing in-stream samples following the third stage and following each succeeding stage; continuing said acid contacting and said testing until the fraction is found to be substantially free of polar organic substances, as evidenced by relatively low dry-point, no sludging coloration with concentrated phosphoric acid, a comparatively high stability to actinic action, and the absence of mineral spirits odor and kerosene smell; and then finally removing inorganic contaminants by aqueous caustic scrubbing and also by absorbent clay contacting.

9. A process for manufacturing aromatic free depolarized naphtha from medium and low boiling petroleum distillates, characterized by: continuously contacting the petroleum fraction with strong sulphuric acid in at least three stages; testing in-stream samples following the third stage and following each succeeding stage for dry point, sludging coloration with concentrated phosphoric acid, stability to actinic action, and presence of mineral spirits odor and kerosene smell; continuing said sulphuric acid contacting and said testing until said tests show the fraction to be substantially free of polar organic substances; and then finally removing inorganic contaminants by aqueous caustic scrubbing and also by absorbent clay contacting.

10. A process for manufacturing aromatic free depolarized naphtha from petroleum distillate, characterized by: contacting the petroleum fraction with strong sulphuric acid in at least three stages; testing in-stream samples following the third stage and following each succeeding stage for dry point, sludging coloration with concentrated phosphoric acid, stability to actinic action, and presence of mineral spirits odor and kerosene smell; continuing said sulphuric acid contacting and said testing until said tests show the fraction is substantially free of polar organic substances and higher boiling organic material; and then finally removing inorganic contaminants by aqueous caustic scrubbing and also by absorbent clay contacting.

11. A process for manufacturing aromatic free depolarized naphtha from medium and low boiling petroleum distillates, characterized by: contacting the petroleum fraction with strong sulphuric acid in at least three stages; testing in-stream samples following the third stage and following each succeeding stage for dry point, sludging coloration with concentrated phosphoric acid, stability to actim'c action, and presence of mineral spirits odor and kerosene smell; continuing said sulphuric acid contacting and said testing until said tests show the fraction is substantially free of polar organic substances and higher boiling organic material; and then finally removing inorganic contaminants by aqueous caustic scrubbing and also by absorbent clay contacting.

12. A process for manufacturing aromatic free depolarized naphtha from petroleum distillate, characterized by: continuously contacting the petroleum fraction with strong sulphuric acid in at least three stages; testing in-stream samples following the third stage and following each succeeding stage for dry point, sludging coloration with concentrated phosphoric acid, stability to actinic action, and presence of mineral spirits odor and kerosene smell; continuing said sulphuric acid contacting and said testing until said tests show the fraction is substantially free of polar organic substances and higher boiling organic material; and then finally removing inorganic contaminants by aqueous caustic scrubbing and also by absorbent clay contacting.

13. A process for manufacturing aromatic free depolarized naphtha from medium and low boiling petroleum distillates, characterized by: continuously contacting the petroleum fraction with strong sulphuric acid in at least three stages; testing in-stream samples following the third stage and following each succeeding stage for dry point, sludging coloration with concentrated phosphoric acid, stability to actinic action, and presence of mineral spirits odor and kerosene smell; continuing said sulphuric acid contacting and said testing until said tests show the fraction is substantially free of polar organic substances and higher boiling organic material; and then finally removing inorganic contaminants by aqueous caustic scrubbing and also by absorbent clay contacting.

CLYVE C. ALLEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,133,457 Lemmon Oct. 18, 1938 2,183,781 Bray Dec. 19, 1939 2,321,290 Giraitis June 8, 1943 2,335,006 Giraitis Nov. 23, 1943 2,348,609 Cohen May 9, 1944 

1. A PROCESS FOR MANUFACTURING AROMATIC FREE DEPOLARIZED NAPTHA FROM PETROLEUM DISTILLATE, CHARACTERIZED BY: CONTACTING THE PETROLEUM FRACTION WITH STRONG SULPHURIC ACID IN AT LEAST THREE STAGES; TESTING IN-STREAM SAMPLES FOLLOWING THE THIRD STAGE AND FOLLOWING EACH SUCCEEDING STAGE; CONTINUING SAID ACID CONTACTING AND SAID TESTING UNTIL THE FRACTION IS FOUND TO BE SUBSTANTIALLY FREE OF PLAR ORGANIC SUBSTANCES, AS EVIDENCED BY RELATIVELY LOW DRY-POINT, NO SLUDGING COLORADTION WITH CONCENTRATED PHOSPHORIC ACID, A COMPARATIVELY HIGH STABILITY TO ACTINIC ACTION, THE ABSENCE OF MINERAL SPIRITS ODOR AND THE ABSENCE OF KEROSENE SMELL; AND THEN FINALLY REMOVING INORGANIC CONTAMINANTS BY AQUEOUS CAUSTIC SCRUBBING AND ALSO BY ABSORBENT CLAY CONTACTING. 